Integrated-inverter electric compressors having an integrated inverter device are known as compressors for air-conditioners installed in hybrid cars, electric cars, etc. Typically, such an integrated-inverter electric compressor is configured such that an inverter accommodating portion (inverter box) is provided on the outer periphery of a housing accommodating an electric motor and a compression mechanism, and an inverter device that converts DC power supplied from a power source to AC power and applies the AC power to the electric motor through a glass-sealed terminal is mounted therein.
The above-described inverter device is typically configured to include a power system board, on which is mounted a switching circuit composed of a plurality of semiconductor switching devices for converting DC power to AC power, such as IGBTs, and a control board, on which is mounted a control-and-communication circuit, such as a CPU, having elements operating at a low voltage, the two boards being stacked on each other. The two boards are integrally mounted to the outer periphery of a compressor housing, by being accommodated in an inverter case or an outer frame.
These integrated-inverter electric compressors for vehicle air-conditioners are used under severe temperature and vibration conditions. Therefore, the inverter devices are also required to have high vibration resistance, moisture resistance, and isolation. Accordingly, proposals have been made in which an inverter accommodating portion, in which an inverter device is mounted, is filled with a gel-like resin material and in which the control board is placed so as to float in a gel-like resin material (for example, see PTLs 1 and 2). A proposal has been made in which three boards, namely, a metal board, a control board, and an interface board, are stacked in a resin case, a power semiconductor surface of the metal board is covered with a gel material, and a space from the surface thereof to the top surface of the control board is covered with resin (for example, see PTL 3).